Method and apparatus for classifying solids



13, 1940. E. P. MCDONALD 2,211,068

METHOD AND APPARATUS FOR CLASSIFYING SOLIDS Filed Dec. 24, 1937 3 Sheets-Sheet l INVENTOR E/e/vEsT P McDo/w w ATTORNEY Aug. 13; 1940- E. P. M DONALD METHOD AND APPARATUS FOR CLASSIFYING SOLIDS Filed Dec. 24, 1937 3 Sheets-Sheet 2 EIK FIG. 5.

INVENTOR EPNEST P MCDONALD ATTORN EY Aug. 13, 1940.

E. P. M DONALD METHOD AND APPARATUS FOR CLASSIFYING SOLIDS Filed Dec. 24, 1937 &\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 3 Sheets-Sheet 5 INVENTOR EPNEsT P MCDONALD ATTORNEY Patented Aug. 13, 1940 UNITED STATES METHOD AND APPARATUS FOR CLASSIFYING SOLIDS Ernest Percy McDonald, Sacramento, Calii.'., as-

signor to Albert E. Vandercook, Sacramento, m

Application December 24, 1937, Serial No. 181,671

80laims.

This invention relates to method and means for classifying solids and particularly to the hydraulic classification or separation wherein a pulsating stream of fluid such as water acts on ore pulp or the like to effect classification in accordance with the settling rate of the solid constituent of material to be classified.

An object of the invention is to obtain uniform classification and to this end I provide method and means for regulating and controlling the generation and application of impulses of water or other fluid to control the classification.

Certain features of the invention reside in obtaining uniform classification in spite of a source of water or other fluid of variable pressure in obtaining a desired range of frequency or pressure for the impulses, in generating the impulses with a self acting valve, in obtaining a range of difierent pressures for the same frequency of the impulses and in obtaining a series of impulses uniform in force and frequency whereby uniformity of classification is obtained.

Other features of the invention relate to improvements in certain apparatus for carrying out my invention namely, in a pressure regulator for regulating the pressure of the water supply, a tank for storing a low head of water, thus regulated, under an air cushion, with means for adjusting the pressure of the air cushion to thereby regulate the acceleration of the water entering the pulsator, a pulsator for generating the impulses of water and a hutch for subjecting the ore pulp, or the like, to the impulses of water and for collecting the concentrate.

For further details of the. invention reference may be made to the drawings wherein:

Fig. 1 is a schematic view of a classifier circuit according to the invention.

Fig. 2 is a sectional elevation of the hutch.

Fig. 3 is an enlarged sectional elevation of onetype of valve which may be used in the hutch of Fig. 2.

Fig. 4 is a sectional elevation of one type of pressure regulator valve.

Fig. 5 is a sectional elevation of a modified type of bellows which may be used in the pressure regulator of Fig. 4.

Fig. 6 is a sectional elevation of a modified type of a flexible member which may be employed to operate the valve of the pressure regulator in Fig. 4.

Fig. 7 is a perspective view partly in section of the tensloning means which may be employed to regulate the valve of the hutch Of Fig- 2- A. modifled and preferred form of this tensioning means is shown in the sectional elevation in Fig. 12.

Fig. 8 is a sectional elevation of a pulsator.

Fig. 9 is a sectionalelevation of a modified and preferred form of pulsator. 3

Fig. l 10 is a sectional elevation of a further modification of the pulsator of Fig. 8.

Fig. 11 is a sectional elevation of a modified and preferred form of valve for the hutch of Fig. 2. l

tion.

Referring in detail to the drawings, the classifier circuit in Fig.1 comprises a ball mill I which is supplied with water from a pipe or other source 15 2. The ball mill i is also supplied with ground ore as is well understood, from a bin or other 7 source not shown. The outlet from the ball mill l is led by way of conduit 3 to the top of an inclined screen 4. The-screen 4 is arranged in a' the bottom of a sluice section 5. The tailings discharge from the sluice section 5 is led by way of conduit 6 to the classifier 'lwhich has a tailings discharge conduit 8 and also a return conduit 9 leading to the ball The sluice 5 and its screen 4 are arranged at the'top of a hutch iii in which the solid constituent of the ore pulp supplied thereto from the ball mill l or other source of a suspension of solids, is classified in accordance with the settling 0 The hutch I0 is provided with one or more 40 windows 15 through which the collection of concentrate may be observed, the concentrate passing downwardly from the hutch with a volume of water which can be regulated by the valve i6.

I have discovered that uniformity of operation of the hutch In, that is to say, uniformity of classification of the solids, depends upon the uniform velocity of the fluid and the frequency of the impulses supplied to the hutch ill by the con- 50 duit Ii. Furthermore in treating different materials it is desirable to be able to change not only the frequency of the impulses and-not only to maintain these impulses at a sustained or uniform force, but it is also desirable to be able to 55 10 Figure 12 is a sectional elevation of a modificaindependently change the frequency orthe force of these impulses as generated, and to regulate the velocity of water passing hutch valve I46. All of these desiderata are accomplished by my invention.

Generally speaking, the function of the pressure regulator i4 is to deliver from a fluid source such as 2 which is not constant in pressure, a constant pressure supply of water or other fluid. This pressure regulator l4 also constitutes a means for changing the frequency and the force of the impulses, as will be described hereafter in further detail.

The function oi. the storage tank It is to store the fluid from the regulator I4 under an air cushion in order to accelerate the, delivery of fluid from tank I3 to the pulsator I2. Furthermore, I provide valve controlled inlet 14 for regulating the air volume above the liquid in tank I2 whereby to vary the head of fluid above the outlet I! from the tank I! whereby to control or regulate the frequency and force of the impulses generated by the pulsator l2.

Generally speaking, the function of the pulsator I2 is to generate fluid impulses due to the flow of fluid therethrough. For a given adjustment, the force of these impulses is sustained due to being generated by a substantially constant pressure acting on a substantially constant mass and head of water. The frequency thereof may be varied through a wide range, such as from 100 to 1000 or more per minute. By high? frequency I mean frequencies in this range. For the particular ores with which I have dealt, I have used and prefer a frequency between 300 and 500 per minute. These impulses are uni-directional, that is free from a suction cycle such as obtains with certain types of well known plunger operated jigs. The pulsator I2 is provided with means to vary the frequency and concomitantly the force of the impulses. v

While the circuit in Fig. 1 illustrates one manner in which my classifier may be employed, it will be apparent that it may be used in other manners, for example, for the classification of sand which may be supplied to the screen 4 from a pump, or otherwise.

The various pieces of apparatus which individually and in combination comprise my invention will now be described in detail and thereafter a more detailed description will be given of the operation of these elements separately and in combination.

The pressure regulator l4 illustrated generally in Fig. 1 and in detail in Fig. 4, is similar somewhat to the pressure regulator shown in my U. S. Patent 2,025,603 issued December 24, 1935, for Pressure control valve. However, I have modifled and improved my patented valve in certain respects.

As shown in Fig. 4 the pressure regulator cornprises a bellows I8, most of the inside of which is filled with a non-volatile liquid l9, such as lubricating oil or glycerine. The bellows l8 has opposed rigid heads 20 and 2|. The head 2| like my patented valve has a tube 22 mounted therein for the admission of the fluid H to the interior of the bellows. This tube extends below the level of the liquid l9 and the top of this tube 22 is sealed for example by the cap 23 which is soldered over the top thereof and to the top of the head 2| after the bellows is partially filled with liquid. The lower head 20 is provided with a recess 24 which receives the stem 25 of a valve 26. The valve 26 is provided with a valve seat 21, the valve 24 controlling the flow of water or other fluid from the inlet 24 to the outlet. The valve 26 is urged to its seat by a spring 24 mounted in a hollow spring barrel 2| which retains the valve seat 21 in its proper position in the casing 22 as shown in the drawings by reason of being retained by the cover 22 which issuitably fastened to the casing 22 by bolts or other fastening means 24. At its upper end the spring 2| bears on a spring cap 26 which in turn bears on the head of the valve 22.

The outlet 22 is provided with a passageway 26 which communicates with a bellows chamber 21 which is provided by the casing 24. The casing 22 is provided with a ridge or stop 3! against which the periphery of the upper head 2| is adapted to abut, which thereby prevents collapsing the bellows ii an undue amount or beyond the allowable working stroke. The head of the valve casing is provided with a centrally threaded aperture 4| in which is threaded stem 42 which serves as an adjustable abutment for the top bellows head 2|. The lower end of stem 42 is rounded as shown and is received in a similarly shaped seat 42 in the head 2|.

The pressure regulator in Fig. 4 functions in somewhat the same manner as my patented valve, namely, the passageway 22 communicates the pressure conditions in the outlet 22 to effect operation of the valve 26, this valve opening when the combined force exerted on the upper face of bellows head 20 exceeds the combined force exerted on the lower face of bellows head 20 and that due to the spring II.

In order to make it possible to vary the gas pressure in the space above liquid is, I have mounted in the upper head 2| a nipple 44 having a check valve 45 which is held to its seat by a spring 46. The nipple 44 has a passageway extending therethrough as shown and it is accessible from the exterior of the casing 38, by reason of the fact that it extends into a nipple 41 mounted on the casing head 40. A threaded cap is fitted on the nipple 41 and seals the space between the bellows l6 and the valve casing 38 and on its removal of course permits an air pressure line to be placed in face to face contact with the upper end of nipple 44 to admit air or other gas under pressure to the interior of the bellows I 2. A gauge (not shown) may be employed to determine how much pressure is admitted to the bellows i2, and obviously if too -much pressure is inadvertently admitted, a pin or the like, may be used to unseat the valve 45 to release the pressure to the proper amount.

For example, if the pressure in the outlet 29 is so high that the gas above liquid i9 is greatly compressed, then only a slight change in the movement of the stem or abutment 42 will make a substantial difference in the operation of valve 26. Under these conditions we may obtain a small difference in the operation of valve 22 for a larger range of movement of stem 42 by admitting air or other gas under pressure in the space above liquid is whereby a given range of movement of stem 42 will now make a smaller percentage difference in the change in the gas volume than it did before. In other words, varying or adjusting the gas pressure above liquid l9 serves to adjust the ratio of the change in this gas pressure to the vertical movement of adlusting screw 42.

The lower casing head 23 is provided with a screw threaded opening 49 having a screw threaded plug 50 fitted therein. If desired, this opening 49 may serve as a clean out opening, or alternately, it may serve as the main inlet to the valve, in which case the inlet 28 would be plugged. I V

Fig. 5-shows a modification of the bellows of Fig. 4 wherein a dashpot 5| connects the bellows heads 20 and 2| to prevent vibration or chattering of the lower head 29 and the valve 26 operated thereby. The dash pot 5| comprises a piston element 52, screw threaded into the upper head 2| and having a piston head. 53 which reciprocates in a cylinder 54 screw threaded into the lower head 29. The cylinder 54 'is provide with a screw threaded cap 55 which serves as a guide for the rod of the piston 52. Also the cap 55 and the cylinder 54 are provided wi h vents 56 and 51 respectively in order that the fluid l9 may circulate in the cylinder 54.

Fig. 6 illustrates a further modification of the pressure regulator of Fig. 4 and wherein I employ, instead of the bellows l8, a flexible diaphragm 58 of acid or chemical resisting material such as rubber. This diaphragm 58 is provided with a corrugation 59 to increase flexibility and it is provided on its lower side with a reinforcing metal plate 6|] in which the top of the stem of valve 25 is seated. In this case, the cap 8| seals the chamber 62 above the diaphragm 58, and in. the chamber 62 I do not employ any fluid as in Fig. 4 but instead merely employ a desirable air or gas pressure, preferably higher than atmospheric, which is admitted to the chamber 62 through the valve controlled inlet 63. The valveinlet 63 comprises a nipple having a central port 64 controlled by a check valve 65 which is urged against its seat by spring 66 held in position by screw threaded plug 61. The nipple.63 is provided with ports 68 as shown, communicating with the chamber 62. The top of nipple 63 is provided with a screw threaded cap seal 69.

It will be apparent that the construction shown in Fig. 6 will be useful in cases where bellows |8 of Fig. 4 is not made in suitable sizes ofvmaterials other than brass and where the fluid controlled by.the valve 26 is of such a nature, such as cyanide solution, as would attack this metal.

As shown in Fig. 1, the outlet 29 of pressure regulator I4 is connected by conduit 18 to the inlet H in the side of the tank I3. The top of tank I 3 is sealed, whereby an air cushion is provided in the space 13 above the level of the liquid such as water in tank iii. The top of tank I3 is provided with a valve controlled inlet 14 which is of the same construction as thatshown for the chamber 62 in Fig. 6. The tank I3 is provided with a sight glass 14' in order to be able to see the level at which the liquid stands in the tank l3. The tank I3 is provided with an oultet |l leading to the pulsator l2. By means of the valve controlled inlet 14 I can increase (from an air pressure line not shown) or decrease (by pushing valve 15 away from its seat) the gas volume of the air cushion 13 to thereby adjust the head of water above outlet 1, to thereby adjust the head of air cushioned water acting on pulsator l2.

The tank i3 is of such diameter, viz. one foot, as to reduce agitation so that air will not be entrained in the water supplied from tank I 3 to the pulsator 2. When the valve in pulsator |2 opens,

let 18 connected to tank I! and an outlet 11 connected to hutch l8.

As shown in Fig. 8, this form of pulsator comprises two flanged casing members 18 and 19 held together by suitable means such as bolts 80. The lower casing member 18 between the inlet 16 and outlet 11 is provided with a valve 8| and a seat 82 therefor. Also the lower casing member 18 is provided with a spider having a centrally disposed guide 89 for the downwardly extending stem 84 of the valve 8|. The valve 8| also has an upwardly extending stem 85, the lower portion of which is screw threaded at 86 and provided with a nut 81 to retain the valve 8| in position on the stem against a shoulder 88. The top of valve stem is screw threaded into a nut or boss 89 which is formed or secured as by welding to the upper face of the lower bellows head 90. The bellows 9| also has an upper head 92 which bears against a screw threaded stem 98 mounted in a central aperture in the top wall of casing 19, similar to the adjustable abutment 42 of Fig. 4.

The lower casing member 18 is provided above the valve 8| with a spider 94 which serves as a support for the lower end of spring 95, the upper end of which bears against the lower face of bellows head to urge the valve 8| towards an open position, acting against a certain predetermined pressure inside the bellows 9|.

In order to restrict the air or gas space within the chamber formed by bellows 9| to a small fraction of the volume of said bellows, I provide inside of said-bellows a sealed cup or chamber 96 integral with or suitably secured to the'lower face of the upper rigid bellows head 92. The bottom of cup- 98 is provided with a recess 91 to receive the nut 89 when the valve 8| is raised.

In order to vary the gas pressure in the space within the sealed chamber defined by the exterior of cup 96 and the interior of bellows 9|, I provide a conduit 98 which opens at its lower end into the space outside of cup 96 and within bellows 9|, and the upper end of which terminates in a nipple 99 serving as a valve controlled inlet whereby air or gas under pressure greater than atmospheric may be admitted inside of bellows 9| and outside of cup 96. The valve controlled inlet or nipple 99 is accessible from the exterior of casing '19 by reason of the fact that it extends through an opening in the top wall of casing 19, this opening having a screw threaded nipple I80 therein with a cap seal |0| thereon.

It will be noted that the area of the lower bellows head 98 is greater than the area of valve 8| whereby fluid pressure admitted at inlet 16 causes the valve 8| to open, thereby permitting an impulse of water to flow past the valve and through outlet 11. As soon as valve 8| opens, the

to flow to outlet 11 at a frequency and force depending upon a number of factors.

Assuming that all operating conditions are constant and adjustments made, the effect of separately varying the pressure regulator |4, air

cushion I3, and pulsator 2 will now be described. The effect of turning the stem 42 to increase the pressure within the bellows l8 and on lower bellows head II will correspondingly increase the level at which the pressure is regulated to be constant in the outlet 2! for the following reasons. Assuming valve 2! to be open and in a state of rest, the force of the gas pressure within the bellows I8 and acting on the lower head II which tends to move valve 28 away from its seat, is equal to the sum of he force of spring ll and the force of the fluid pressure in the bellows chamber 81. still assuming that the gas pressure within bellows II is higher than it was before it will be seen that a higher pressure in outlet 2! will now be required to overcome the pressure within the bellows II and move the valve 26 to a closed position. In other words, when the valve 18 is open and at rest, the force of the gas pressure (a) equals the sum of force (b) of the spring II and the force (c) of the fluid in bellows chamber 31. In order for the valve 2| to remain in an open position at rest under operating conditions with a higher gas pressure in bellows It, that is, with a higher value of (a), it is obvious that a higher valueof namely, the pressure in the bellows chamber, is required in order to satisfy the above equation, the force (b) of the spring remaining substantially constant for both conditions. On the other hand, if it is desired to regulate for a lower pressure in outlet 2!, the stem 42 is turned so as to decrease the gas pressure within the bellows ll. Also, the gas pressure within bellows It as well as the working range of this bellows and the valve controlled thereby may be adjusted by varying the air pressure admitted through nipple 44 to the space above fluid It as described above.

The result of increasing the operating pressure of the fluid leaving outlet 29 is to increase the head of water in tank 12 with a consequent increase in the pressure of air cushion 13 and to correspondingly increase the pressure'at which water or other fluid is admitted to pulsator l2. Increasing the fluid pressure at the inlet 18 of pulsator I2 serves to increase the opening stroke of pulsator valve ll whereby this valve in having an increased excursion takes a longer time for opening and closing, namely, the frequency is lowered.

Any increased pressure within tank I! will increase the velocity of fluid discharged from the tank and also the velocity of fluid entering inlet 76 and also increase the pressure acting on the lower face of bellows head 80 and the upper face of valve 8|. As a result of the increased pressure between these surfaces and the increased velocity of the water entering inlet 16, the differential force on the lower face of bellows head BI and the upper face of valve II will be increased. The resulting increased pressure causes the bellows head 80 and all parts fastened thereto to have a longer reciprocating stroke. As a result of the above mentioned increased reciprocating stroke, the frequency of operation of this unit will be decreased.

Even though the higher pressure gives an increased acceleration of bellows head 90 and parts attached thereto, nevertheless experience has shown that an increase in the pressure at inlet It results in lowering the frequency of operation of valve Ii. a

Changing the adjustment on the pressure creaseofpressurewithintank I8 willincrease the volume of water passing through thehutch valve I" and decrease the frequency of impulses. Zlhe frequency may be increased to its previous value by increasing the pressure within bellows Ii with a net increased force of impulses. The resulting increased velocity of water through the hutch valve I may be regulated as desired by use of the hutch valve adjustment I".

Under constant operating conditions, an increase in pressure within the space inclosed by bellows II and cup 9 will increase the frequency, reduce the stroke of valve II and decrease the volume of water passing through outlet 11. The rate of acceleration of the water passing through outlet 11 will be greater, but due to the time factor involved and the restricted passage below valve II, the velocity of water passing through outlet ll will be less than would be the case under the same pressure conditions with a longer stroke.

By these various adjustments I can regulate the frequency, the velocity of water passing the hutch valve I and the volume passing this valve.

It will be apparent that for each adjusted condzltion of any one or two of the three elements, namely, regulator ll, tank I! and pulsator if, there is a wide range throughout which the remaining element or elements may be regulated and adjusted whereby the frequency and force of the impulses delivered by pulsator I! may be independently regulated and adjusted as desired. A modified and preferred form of pulsator i2 is shown in Fig. 9 wherein the spring 95 of Fig. 8 is omitted. Also the upper valve stem 85' is secured for example by being screw threaded into the lower face of bellows head ill whereby the upper surface of this bellows head is flat and the lower wall of cup 88' is fiat making it unnecessary to employ the recess 91 of Fig. 8. Also, the lower valve casing II is provided with a spider I02 having a centrally disposed guide bearing I" for the valve stem 85'.

By omitting the spring from the pulsator in Fig. 9 I have substantially increased the capacity of the pulsator for the following reasons.

It is evident that any force exerted on the lower face of bellows head 80 to raise valve 8| from its seat under operating conditions must be overcome by pressure energy within bellows II and outside cup 96. By eliminating spring pressure on the lower bellows head llthlsenergy may be utilized in' increasing the necessary pressure below head ll and above valve 8|. Due to this increased pressure, the force of impulses leaving discharge outlet 11 are accordingly greater and for this reason the capacity of this pulsator is increased for a given pressure within bellows ii and outside chamber 98'. In other words, if the spring is employed we must use inside of this bellows I a pressure which will overcome it without affecting the discharge through outlet 11.

The force of impulses discharged through outlet 11 in Fig. 9 depends on the required diflferential force between the lower bellows head II and upper face of valve II. By eliminating spring ll this differential or force will become greater with a resulting increased capacity of the pulsator for a given pressure within bellows ii and outside cup 96. In other words, I can get substantially the same operation out of the pulsator shown in Fig. 9 as in Fig. 8 with a lower pressure in the bellows ll as this pressure does not havetobebmltuptoapointtooppoaea spring pressure.

The life of the pulsator shown in Fig. 9 will be longer than the life of the pulsator in Fig. 8 under the same operating conditions, as to frequency and force of impulses delivered from the output, for the reason that the bellows 9I' of the valve in- Fig. 9 canbe-operated under a lower internal pressure than the bellows 9| of Fig. 8, bearing in mind that the life of a bellows depends onthe pressure under which the bellows operates.

A valve, controlled inlet I04 is provided for the pressure regulator in Fig. 9 similar to the one described for the regulator in Fig. 8, in order to adjust the pressure between the inside of bellows 9| and the outsideof cup 90'.

A modified form of pressure regulator of Fig. 8 is shown in Fig. 10, a flexible diaphragm I05 being used instead of a bellows. Diaphragm I05 is of acid or chemical resisting material such as rubber for use with fluids such as cyanide solution which would attack a copper or brass bellows. Diaphragm I05is provided with a corrugation I06 for flexibility and is clamped between an upper casing member I01 and a lower casing member I08. Member I01 is provided with a cap seal at I01 and a valve controlled inlet at I09 similar to the construction shown-in Fig. 6. At opposite sides of diaphragm I05 I provide two reinforcing metal plates [I0 and III which are clamped between a shoulder II2 on the valve stem H3 and a nut II4 screw threaded on the top of the valve stem.

As shown in Figs. 1, 2 and 7 the hutch I0 comprises a sluice 5 having a screen 4 in the bottom thereof. This screen covers the top of the hutch I0 which tapers to a valve seat H0. The valve III which is shown in detail in Fig. 3 may comprise an elastic ball of rubber or the like, mounted on a valve stem I I2 which is carried at its lower end in a slide bearing H3 and also guided by a bearing H4 at the screen and at its top by a loosely flttin'g guide H5. The lower portion of the valve stem H2 is secured to the valve III- by a washer IIG outside of the valve and by a washer II1 inside of the valve. The valve stem I I2 is also secured to valve I I I at the top thereof by the outside washer H8 and by the inside washer II9. Means are provided for inflating ball III to a desired pressure and to this end the valve stem is separable at the screw threaded joint I20, the lower section of the joint having a passageway I2I therethrough which is controlled by a spring pressed check valve I22.

The bearing II 4 is shown in further detail in Fig.7 and comprises a cross member I23 which supports a bushing I24 in which the valve stem I I2 slides. The bushing is provided with a flange I25, the under side of which engages the screen and this bushing is clamped in position: as shown by means of a nut I26. The sluice 5 is provided with two uprights I21 and I28 which support a cross piece I29 in which the guide I I5 is mounted. This guide makes a loose fit with the valve stem II2 andis provided with a non' circular cross section which fits with the upper end of valve stem I I2 having a corresponding shape such as square, in order to prevent it fromrotatlng when manipulating the thumb nut I30 to regulate the tension on the valve III. By regulating the tension onthe valve III I can control the stroke of this valve and consequently the velocity of liquid entering the hutch III. The thumb nut I30 is screw threaded onto an upper portion of the valve stem H2 and a spring I3I is provided be- 5 tween this thumbnut and the under side ofbearing II5. Also a spring I 3| is provided between the upper side of bushing I24 and the under side of thumb nut I30.

The hutch valve III, and the same is true of the modification shown in Fig. 11, op ns and closes with each fluid impulse acting on the valve. As the force of an impulse increases, the valve opens to admit the liquid to the hutch, thus agitating the pulp and causing the heavier concentrates to settle upon or near the valve seat. As the force of each pulse decreases, the valve III moves towards a closed position to decrease the velocity of the liquid therethrough while permitting some of the fluid in the hutch to leak past the valve III and carry with it the concentrate. By employing a reciprocating fluid pressure operated valve such as III in the hutch I0, I automatically seal off the chamber below the'valve I I I from the hutch chamber above this valve except when impulses are admitted to the hutch cham- 7 her, above the valve, and except during the closing stroke of the valve when the concentrate is separated from the pulp at the valve.

If desired, I mayemploy one or more deflectors I32, I33 inside of hutch I0 and above valve III in order to more uniformly distribute the force of the impulses over the area of the screen 4.

In order'to prevent the solids in the ore pulp, or the like, which pass over "the screen 4 from settling between valve stem H2 and the .bushing I24, as may be the case in Fi 2, I prefer to use the modification illustrated in Fig. 12 wherein the valve stem H2 is loosely enclosed within a bushing I35 which has a height greater than the normal level of the pulp in. the sluice 5. Bushing I35 is provided with a flange I38 above the screen and with a nut I31 below the screen. Bushing I35 is suitably secured to a cross piece I 38 which extends above the level of the pulp, in sluice 5 and is suitably fastened to the sides of this sluice. A guide for the top of valve stem H2 in this case is provided by a bushing I39 having a non circular, such as a square, in-

terior which has a working fit with the similarly shaped top of valve stem II2. Bushing I39 is carried by a top cross piece I40 supported by uprights Ill and I42 arising from and suitably secured to the sides of the sluice 5. The valve stem H2 is provided with a thumb nut I43 and with springs I44 and I45 to regulate the velocity of water passing hutch valve I46.

A preferred form of fluid operated hutch valve is shown in Fig. 11 wherein a conical shaped ,valve I46 having downwardly sloping sides and 05 Referring to Fig. 1, the velocity of the fluid impulses delivered from pulsator I2 to the hutch I0 may to some extent be controlled byregulating the opening of valve I6 which controls the discharge from the hutch III of some of the water therein with the concentrate. Also, an operator may look through one of the windows I5 and observe the nature of the concentrate passing the valve and at the same time regulate the thumb nut I30 to change or regulate the operation of the hutch valve III in order to get the best operating conditions.

Without limiting the invention to the following figures, the following is given as an example of the pressure conditions which may be employed. The resulting force of the operating pressure within pressure tank ll, acting on the lower surface or bellows head II. must overcome the resultingdownward force acting on valve II and the downward force acting on the upper surface of bellows head 80. Under these conditions the liquid pressure within tank ll, whichiis the same as the liquid pressure delivered by pressure regulator ll, must be higher than the pressure within the space included within bellows it and outside displacement cup 98. Under working conditions I may give as approximate working pressures, four pounds per square inch in tank It and three pounds per square inch within bellows ll.

Various modifications may be made in the method and means herein disclosed without departing from the sphere of the invention.

I claim:

1. An hydraulic classifier of solids comprising the combination oi a pressure regulator adapted to be connected to a water supply, a storage tank supplied by said regulator and having a closed top to air cushion the water therein, an automatic pulsator supplied by said tank and adapted to be operated at a high frequency by the flow of water therethrough, a fluid tight bellows controlling the operation oif said valve, means for adjusting the pressure within said bellows, means for varying the force exerted on said valve by said bellows, a hutch associated with said valve, and an adjustable spring controlled, fluid pressure operated valve in said hutch for admitting unidirectional impulses of water from said automatic pulsator to said hutch and for permitting discharge of the concentrate.

2. An hydraulic classifier of solids comprising the combination of a hutch chamber having a top adapted to receive pulp at one side and adapted to discharge tailings at the other side, said hutch chamber converging downwardly to a valve seat, an upwardly opening fluid pressure operated valve for said seat, a concentrate chamber below said seat and in communication with said hutch chamber, means for admitting fluid impulses below said valve to operate said valve, and means for controlling the flow of concentrate from said concentrate chamber.

3. In apparatus of the character described, a hutch comprising a casing having a port adjacent its bottom for the admission of pulsating liquid and shaped to cause the discharge of concentrate through said port, a screen adjacent the top of the casing, a pulsation-responsive valve controlling said port, and a liquid actuated pulsator for delivering a liquid under regular pulsations to said chamber by way of the valved Port.

4.Intheapperatusdeflnedinclaim8,yieldingmeanstendingtoboldeaidvalveinitecioled position, and adjusting means for MIDI the resistance or said yielding means to opening movement of the valve.

5. Apparatus of the character described, comprising a hutch provided with a screen and having a pulsation-responsive valve for controlling the inflow of liquid thereto, a high frequency pressure-responsive pulsator valve connected to said. hutch to supply pulsating q id thereto, adjustable means for varying the frequency of said pulsator valve, adjustable means constituting a source of liquid under variable constant pressure for passage through said pulsator valve, and still further adjustable means tor varying the resistance to opening movement of said pulsation-responsive valve.

6. An hydraulic classifier of solids comprising the combination oia hutch having a chamber with an ore pulp inlet and a taiiings outlet at its upper, end, a sitting screen positioned in the path of liquid flow to and irom said hutch, a pulsator, a pressure regulator, means to pass liquid in series through said regulator, pulsator and hutch, means for adjusting said regulator to supply the liquid to said pulsator at a desired constant pressure, a valve in said pulsator and means within said pulsator responsive to the pressure of liquid supplied thereto for causing said valve to intermittently open and close to supply a series of substantially constant impulses to said chamber, a second valve within said chamber arranged to permit the inlet of liquid and the discharge of concentrate, and adiustable tensioning means for said second valve whereby it may be adjusted to pass liquid at a desired velocity into said chamber and through said screen.

'I. An hydraulic classifier of solids comprising, in combination with means for pulsating a liquid under substantially constant head, a hutch having a chamber converging downwardly to a valve seat, a valve for said seat, means ior admitting a pulsating water stream below said valve, and adjustable tensioning means yieldingly urging said valve downwardly toward said seat and so controlling said valve that the range of movement of said valve may be varied to vary the stream velocity therethrough.

8. An hydraulic classifier of solids comprising the combination oi! a pulsator, an inlet and an outlet therefor, said'pulsator comprising a valve adapted to be operated by liquid flow therethrough for generating high frequency unidirectional liquid impulses, a hutch having an adjustable spring controlled valve for controlling the admission of said liquid impulses to said hutch, and means upon said pulsator for varying the frequency of said impulses.

ERNEST P. MCDONALD. 

